Internal-combustion engine



March 8, 1927.

H. E. DICKINSON INTERNAL COMBUS TION ENGI NE I Filed April 29, 1925 9,1.

mnunmmmmlli affotum Patented Mar. 8, 1927.

UNITED STATES I 1,620,446 PATENT OFFICE.

HARRY E. DICKINSON, OF SAN ANTONIO, TEXAS.

llINTERNAL-COMBUSTION ENGINE.

Application filed Apri1,29, 1925.

This invention relates to internal combustion engines and part'icularly'to improvements in valve gear, the object of the invention being to construct a valve or push rod of adjustable length which will maintain its adjustment, unaltered, notwithstanding the continuous succession of impactive blows to which it is subjected incidentally to the operation of the internal combustion engine.

The problem of constructing valve operating mechanism which will maintain uniform clearance between the valve stem andtappet or rocker arm, and so remain in permanent adjustment and silent in operation, has engaged the attention of automotive engineers for many years but up to the present time no effective solution has been found.

The present invention seeks to obviate the hitherto uncontrollable variation in the length of the valve or push rod which is the cause ofobjectionable noise and displacement in valve adjustment. lVhile I have chosen an overhead valve mechanism as the illustrative embodiment of the invention upon which the following description is based it is to be understood that the remedy afl'orded by my invention is equally applicable to valves of the L-head type, the rocker arm and push rod being 'l'unctionally but sections of a jointed valve stem, so made as to be adaptable to the structural requirements of the overhead valve arrangement.

In the drawing Figure 1 is a side elevation, partly in section, of valve operating mechanism embody ing my invention.

F lgure 2 1s a section taken along the line 2-2 of Figure 1.

Figure 3 is a sectional View, shown inexposed relation of parts which cooperate in the functioning of my invention.

Figure 4 is an elevational View partly in section of a threaded rod provided with lock nuts, the same being used to illustrate a physical principle underlying my invention. Referring now in detail to the several figures, the numeral 1 represents a cam on the cam shaft adapted to reoiprocaloly.actuate the push rod 2, the latter co-acting with one end of the rocker arm 3, the opposite end of which engages the valve stem 4. The clearance space between the valve stem and rocker arm is indicated at'5. The push rod is made in sections 3 and 4, the former of which threads into a socket in the other, so

Serial No. 26,720.

explained, reference being had to the diagrammatic illustration shown in Fig. 4.

It is well known that when a blow isstruck upon one end of a metallic rod, the force of said blow is transmitted to the other end thereof by a wavelike impulse which traverses the rod. A blow delivered to the upper end of the threaded rod a, Figure 4, by means of the weight 6 produces a longitudinal compression of a portion of said rod causing a lateral swelling thereof indicated at c. This compression pha e of the wave passes downward through the rod, a second position of the same being indicated at d in Figure 4. Following the compression phase of the wave is the attenuation phase which causes the diameter of said rod to shrink in the zone of said phase, as indicated by the reference character 6. In Figure 4 two nuts 7 and g are shown engaging the threads of said rod, the upper one corresponding to the upper section of the push rod and the lower to the lock nut ordinarily used to hold the upper section in adjusted position. ,It will be observed that when the rod a is in passive state the nut 7", acts compressively in an upward direction against the sloping faces of the threads and the nut g acts'compressively downward against the sloping faces of said threads. It is this frictional action of the respective nuts against the faces of the threads (1 that is relied on to keep them locked in position. When lock nuts are used on ordinary bolts or rods they generally work with a satisfactory degree of efliciency due to the fact that bolts and rods in general are subjected to desultory vibrations in any or all directions so that there is no repeated tendency in one direction to dislodge said nuts. But in the case of a push rod for overhead valve operating mechanism a peculiar condition prevails which renders the use of an ordinary lock nut altogether inefficient to prevent the gradual shifting of the upper section 4 of said push rod relative to the lower section.

subjected to a continuous Succession of rapidly repeated blows acting always in 'a direction lon itudinally of said red.

It will be c ear from Figure 4: that whenever the attenuation phase of the wave traversing said rod passes the zone engaged by the nuts f and g, the threads of said rod will be drawn away from the internal threads of said nuts as shown [at E due to temporary diminution in the diameter of said rod so that the longitudinal thrust of said nuts against the sloping faces of the threads ceases to exist and the nuts float on said rod, together, as a unit. It is clear that at this moment the nuts are free to vibrate or move relative to the rod and so to drift downwardly on the inclined plane provided by the helix of the threads. The time interval required for the passage of a single one of the attenuation wave phases is so slight that the nuts 7 and 9 can make but an infinitesimal descent relative to said rod. But with constant repetition the aggregate effect hecomes quite noticeable and the clearance between the. valve stem and rocker arm widens to'such an extent as to make the operation of the mechanism noisy.

In the present invention I prevent drifting of the upper section of the push rod relative to the lowersection by providing the former with resilient means for exerting lateral pressure against the sides of the lower section, which pressure, by reason of the resilient nature of said means is continuously applied throughout the period of passage of the attenuation wave phase, giving the section no chance to become relatively loose. This is accomplished by forming the lower end of the upper push rod section with a tapered portion as shown at Gin Figure 3 and slitting said tapered portion at several places circumferentially, thereby forming resilient "jaws 14. A look nut 7 is provided which freely surrounds the lower push rod section and screws upon a thread B'formed on the upper push rod. section 4. above the tapered portion 6. Preferably the slits 11 do not intersect the thread 8. The lock nut 7 has an internal tapered surface 9, of substantially the same pitch as the tapered portion- 6, which functions, when the lock nut is brought into engagement with the upper push rod section 4, to co-act with the jaws 1d pressing them into intimate contact with the threaded end of the lower push rod section. The jaws are internally threaded as shown at 10.

By preference I provide the upper push rod section 4, just above the taperedv portion 6 and below the thread 8 with a deeply cut groove 12 extending therearound and so my hand.

resiliently engage the threaded portion of the lower push rod section and that when the attenuation wave phase passes through said section the 3aws will resiliently more inwardly retaining their hold upon the push rod. Under these circumstances it is unpossible tor the upper section oi the pushrod to shift its position relative to the lower section and consequently the impactive blows upon-said push rod incident to the operation of the valve have no effect in tending to change the adjustment which deter mines the length of the push rod. The cleartime space between the rocker arm and push rod therefore remains constant indefinitely and the valve operating mechanism does not become noisy.

While I-have here shown what I believe to be a practical and efficient embodiment of my invention it is to be understood that numerous changes and alterations may be made in the details of construction and arrangement of the several parts, wherefore I- do not-desire to-be limited in the purview of my invention except in so far as C0111- pelled by the expressed limitations defined in the claim.

Having described my invention what 1 claim as new and desire to secure by Letters Patent, is z--- I Valve operating mechanism for internal combustion engines including a valve operating element subject to repeated impactive blows, longitudinally delivered, said element comprising a socketed section and a section telescoping therein, said sections beingthreadedly interengaged for varying the length of said element, said socketcd section being formed-with'a tapered lower'end longitudinally slotted at a plurality of points forming yielding jaws substantially surrounding the other section. for exerting resilient pressure laterally thereagainst from different directions, said socketcd section bcing 'rovided with a groove extending circum erentially thereabont adjacent the bases of said slots, and a nut having an internal taper of corresponding pitch to the tapered end of said socketed section, surrounding said other section and threadedly engaging said 'socketed section for drawing said jaws section.

In testimony. whereof I have hereunto set i HARRY E. n onmso u. 

